ELISA stands for enzyme linked immunosorbent assay. In short, it is an antibody test or a test for immune response to things attacking the body such as virus, bacteria and allergens. The test is done in an ELISA plate, also known as a 96-well plate or microplate. The ELISA reader reads the plate.

What an ELISA Reader Does

An ELISA reader measures and quantitates the color differences in the 12 wells of the plate.
An ELISA reader measures and quantitates the color differences in the 12 wells of the plate.

ELISA readers or micro plate readers do spectrophotometry; they emit light at one wave length, and measure the amount of light absorbed and reflected by an object such as a protein. A spectrophotometer measures ultraviolet and visible light.

Additionally, ELISA plate readers can also measure fluorescence and luminescence. Chemical dyes fluoresce or emit one color or wavelength when exposed to light. The amount of reflection, absorption and the color identify, and measure the amount of a substance.

Purpose of an ELISA reader

Researchers can use ELISA plate readers for protein assays.
Researchers can use ELISA plate readers for protein assays.

ELISA readers were designed for measuring antibody tests. They worked so well, the machine has been adapted to other purposes. Researchers use them for protein and enzyme assays. They are also used for HIV detection and quantitation of nucleic acids.

Advantages of ELISA Reader

Spectrophotometers require more sample per measurement.
Spectrophotometers require more sample per measurement.

To use a spectrophotometer or ELISA plate reader, the molecule must be dissolved in solution. A spectrophotometer requires between 400 micro-liters and four milliliters, depending on the manufacturer and model. An ELISA plate reader needs about two to 100 micro-liters; ELISA plate readers use much less of a sample to get a result.

ELISA plate readers measure more samples in a shorter period of time. A spectrophotometer measures one to six samples at a time. Typically, an ELISA plate measures 96 wells in an equivalent amount of time.